Hi,
Thanks for reaching out to us! I’d be happy to help you 🙂
I can see you replied “yes” to the question asking if you deactivated all other plugins. Did you still have the same issue with other plugins deactivated?
Also, could you try to switch to the default theme (Twenty Seventeen) to see if that makes a difference?
If you have any doubts, please have a look at our documentation about Testing for conflicts.
Also, could you please enable WP_DEBUG (https://codex.wordpress.org/Debugging_in_WordPress) and WP_DEBUG_LOG (https://codex.wordpress.org/Debugging_in_WordPress#WP_DEBUG_LOG) ? This will create a debug.log file inside the /wp-content directory.
After that, try reproducing the issue a few times, so that in case there is an error, it will be saved into the debug.log file. Please share that log file with us so we can see if any problem from there.
Please let me know what you find out during the process.
Cheers,
Jeremy